| 摘要 |
A voltage conversion circuit is disclosed. The voltage conversion circuit includes an inductor, a first switch transistor, a second switch transistor, a first resistor, a second resistor and a P type transistor. When an input voltage is larger than an output voltage and a switch signal is transited to low voltage level, a control signal is a clamping voltage and the P type transistor enters into a saturation region, so that a drain voltage of the first switch transistor is a sum of the clamping voltage and a source-gate voltage of the P type transistor. When an output voltage is larger than an input voltage and a switch signal is changed to low voltage level, the control signal is the switch signal and the P type transistor enters into a linear region, so that a drain voltage of the first switch transistor is sum of the output voltage and voltage-drop of the P type transistor. |
| 主权项 |
1. A voltage conversion circuit, comprising:
an inductor, having one terminal electrically connected to an input voltage; a first switch transistor, having a drain connected to another terminal of the inductor, having a gate connected to a switch signal and determining switched-on or switched-off state itself according to the switch signal, having a source connected to a ground voltage; a second transistor, having a drain connected to another terminal of the inductor, having a gate connected to the switch signal, wherein switched-on or switched-off state of the second transistor is opposite to those of the first switch transistor; a first resistor, having one terminal connected to a source of the second switch transistor, having another terminal connected to a clamping voltage; a second resistor, having one terminal connected to another terminal of the first resistor, having another terminal connected to one terminal of an output capacitor and outputting an output voltage, wherein another terminal of the output capacitor is connected to the ground voltage; and a P type transistor, having a source connected another terminal of the inductor, having a gate receiving a control signal and accordingly determining whether to enter into a saturation region or a linear region, having a drain connected to one terminal of the output capacitor, wherein when the input voltage is larger than the output voltage and voltage level of the switch signal is changed from high voltage level to low voltage level, the control signal is the clamping voltage and the P type transistor enters into the saturation region, so that a drain voltage of the first switch transistor is sum of the clamping voltage and a source-gate voltage of the P type transistor, wherein when the input voltage is smaller than the output voltage and voltage level of the switch signal is changed from high voltage level to low voltage level, the control signal is the switch signal and the P type transistor enters into a linear region, so that a drain voltage of the first switch transistor is sum of the output voltage and voltage-drop of the P type transistor. |
